1. Field of the Invention
The present invention is directed to a thrust plate assembly for a friction clutch with automatic wear compensation. The thrust plate assembly includes a housing which is connected or connectable to a flywheel for rotation with the flywheel about an axis of rotation, a pressure plate arranged in the housing so that the pressure plate is fixed with respect to rotation relative to the housing and axially displaceable relative to the housing, an energy accumulator having one side supported at the housing and another side supported at the pressure plate, a wear adjustment device having at least two adjustment elements pretensioned relative to one another for carrying out a relative adjusting movement arranged in the support path of the energy accumulator between the energy accumulator and a first component of one of the housing and pressure plate, and at least one play sensor arrangement for detecting wear including a detection element which acts upon the wear adjustment device to prevent a relative adjusting movement of the adjustment elements and which includes a detection portion that interacts with a second component to detect wear, the second component being displaceable with respect to the pressure plate when wear occurs, and wherein the detection element is movable into a position for releasing the adjustment elements for carrying out the relative adjusting movement when wear occurs by the interaction with the second component.
2. Description of the Related Art
Thrust plate assemblies for friction clutches with automatic wear compensation are known with play sensor arrangements having a detection portion that penetrates an axial through-opening in a pressure plate. The detection portion can easily be tilted in the through-opening and a free end of the detection portion can come into contact with the flywheel. A leaf spring element is fixedly arranged at one end of this detection portion situated at a distance from the flywheel. The leaf spring element extends toward the wear adjustment device and overlaps it so that the wear adjustment device is clamped between the pressure plate and the leaf spring element. Since the leaf spring element is supported at the wear adjustment device, the spring elasticity of the leaf spring causes the detection portion to be tilted in the through-opening and the detection portion is accordingly pretensioned in a friction clamping fit. When wear occurs, the pressure plate moves toward the flywheel causing the detection portion to strike the flywheel. Further movement of the pressure plate causes the detection portion to be displaced with respect to the pressure plate. As a result, the leaf spring element is somewhat relaxed, thereby diminishing its action upon the wear adjustment device. During a subsequent releasing process in which the diaphragm spring releases the wear adjustment device, this wear adjustment device, due to the fact that it is pretensioned for carrying out a wear adjustment movement, executes a wear compensating movement until the pretensioning force of the wear adjustment device for carrying out its wear compensating movement and the counter-force generated by the leaf spring element balance one another.
However, a fundamental problem in the operation of systems of this type is that occurring vibrations or shaking movements can generate a relative vibration between the wear adjustment device and, for example, the pressure plate. It must then be ensured in the disengaged state through the action of the leaf spring element that these vibrations cannot cause the wear adjustment device to be lifted from the pressure plate, which could result in spontaneous execution of a wear adjusting movement. Therefore, it must be ensured that the leaf spring force is sufficiently large to hold the wear adjustment device firmly at the pressure plate in every movement state or operating state. This in turn requires a correspondingly large pretensioning force in the wear adjustment device to pretension the same for carrying out a wear compensating movement. Consequently, these two spring areas or pretensioning areas must finally be overdimensioned with respect to the pretensioning function that is actually to be performed by them.
It is an object of the present invention to provide a thrust plate assembly for a friction clutch with automatic wear compensation such that the components provided therein for carrying out wear compensation are designed in an optimal manner with respect to their actual function and overcome the problems of the prior art.
According to an embodiment of the present invention, the object is met by a thrust plate assembly for a friction clutch with automatic wear compensation having a housing which is fixed or fixable to a flywheel for rotation with the flywheel about an axis of rotation, a pressure plate arranged in the housing so that the pressure plate is fixed with respect to rotation relative to the housing and axially displaceable relative to the housing, an energy accumulator such as a diaphragm spring having one side supported at the housing and another side supported at the pressure plate, and a wear adjustment device arranged in a support path of the energy accumulator between the energy accumulator and a first component of one of the housing and the pressure plate. The wear adjustment device has first and second adjustment elements which are pretensioned relative to one another for carrying out a relative adjusting movement. The thrust plate assembly further includes at least one play sensor arrangement for detecting wear, wherein the play sensor arrangement comprises a detection element which acts upon the wear adjustment device to prevent a relative adjusting movement of the adjustment elements. The detection element also includes a detection portion arranged for interacting with a second component for detection of wear. The second component is displaceable with respect to the pressure plate when wear occurs. The detection element can be brought into a position for releasing the adjustment elements for carrying out the relative adjusting movement when wear occurs by the interaction with the other component.
The thrust plate assembly according to the present invention further includes a stopping element for stopping the detection element in its position for releasing the adjustment elements. Moreover, the detection element has a first application area for acting upon the first adjustment element and a second application area for acting upon the second adjustment element, wherein the adjustment elements are prevented from carrying out the relative adjusting movement when the first adjustment element and the second adjustment element are acted upon by the respective application portions.
An essential characteristic of the thrust plate assembly according to the present invention is that the detection element alone blocks of the wear adjustment device for preventing an unwanted relative adjusting movement , i.e., a force loop or force feedback is provided within the detection element. The wear adjustment elements and the respective detection element accordingly form a self-enclosed unit with respect to forces and there is low risk that individual components will vibrate against one another due to the relatively small masses. Relative movements of the wear adjustment elements and/or the detection element, for example, relative to the pressure plate, do not produce an unwanted wear adjustment because the detection element is not fixedly tied to the pressure plate, as is the case in the prior art. Rather, the detection element according to the present invention is supported at the wear adjustment device.
According to a preferred embodiment of the present invention, the first application area and the second application area of the detection element are pretensioned toward one another. To provide the above-mentioned function of generating a force feedback in a simple manner via the detection element, the detection element may comprise a spring clamp element having first and second leg areas in which the first application area is arranged on the first leg area and the second application area is arranged on the second leg area. Furthermore, the detection portion of the detection element may be provided at the first leg area.
To introduce the force of the energy accumulator in a simple and reliably operating manner, the first adjustment element is supported at a component of the energy accumulator and acts on the second adjustment element. It is preferably provided that the first adjustment element is acted upon by the first application area, i.e., by the leg area of the detection element at which the detection portion is also provided.
To achieve defined movement states when carrying out wear adjustment, one of the adjustment elements is essentially not movable with respect to the first component when the relative adjustment movement is carried out in the wear adjustment movement direction. In the preferred embodiment, the first adjustment element which is also acted upon by the energy accumulator is blocked against movement.
Thrust plate assemblies of the type described above must be constructed in such a way that no imbalance exists during rotary operation. This also means that while wear compensation is carried out the various structural component parts cannot shift in such a way that imbalance is created by carrying out wear compensation. For this purpose, it is suggested that the at least one detection element is held at the first component so as to prevent movement in a wear adjustment movement direction corresponding to the relative adjusting movement. For example, the wear adjustment movement direction can be a circumferential movement direction.
According to a preferred embodiment, when the one adjustment element is prevented from moving in the wear adjustment movement direction, the other adjustment element is blocked by the at least one detection element to prevent movement.
The pretensioning of the adjustment elements for carrying out the relative adjusting movement in a wear adjustment movement direction may be generated by at least one adjusting pretensioning spring. The at least one adjusting pretensioning spring may have one side acting on one of the adjustment elements and the other side acting at another of the adjustment elements or the one component of the pressure plate and the housing. In the embodiment in which the at least one adjusting pretensioning spring acts at respective adjustment elements, the wear adjustment device and the detection element may be arranged as a subassembly which is also completely self-contained in this respect and which finally requires no special coupling to other subassemblies with the exception of the detection portion which must cooperate with a component that moves with respect to another component when wear occurs.
The wear adjustment device comprises two adjustment elements according to the preferred embodiment of the present invention. Each of the two adjustment elements have surfaces that are inclined with respect to a wear adjustment movement direction and are arranged as adjustment rings which contact one another.
In the thrust plate assembly according to the present invention, the second component comprises the housing, a component connected with the housing, or the energy accumulator.
The present invention is further directed to a wear adjustment module, especially for a friction clutch with automatic wear compensation, having at least one adjustment element group with at least two adjustment elements, at least one detection element which acts by a first application area upon one of the adjustment elements of the at least two adjustment elements and acts by a second application area upon another adjustment elements of the at least two adjustment elements and pretensions these adjustment elements relative to one another such that they are blocked to prevent execution of a relative adjusting movement with respect to one another.
A wear adjustment module of this type also ensures that it generates, in itself, a complete force feedback. The wear adjustment module can be added as an assembled component group to a thrust assembly in an assembly process. The risk of an unwanted release of the wear adjustment device cannot occur when oscillatory excitations or vibrations occur because of the complete force feedback within the wear adjustment module.
Also, the wear adjustment module may also include at least one adjusting pretensioning spring for pretensioning the adjustment elements of a respective group of adjustment elements with respect to one another for carrying out the relative adjustment movement.
In this regard, the at least one adjusting pretensioning spring has one coupling area that acts at one of the adjustment elements and another coupling area that acts at another of the adjustment elements of this group or that is arranged for acting upon another component.
The wear adjustment module further comprises a stopping element associated with at least one detection element which cooperates with this detection element for stopping the detection element in a position in which at least one of the adjustment elements of a respective group of adjustment elements is not acted upon to ensure that the detection element remains in the position corresponding to wear when wear occurs. The stopping element allows an adjusting movement to be subsequently performed.
The stopping element is preferably pretensioned in a stopping direction with respect to the detection element.
The present invention is further directed to a friction clutch which has a thrust plate assembly according to the present invention and a wear adjustment module according to the present invention.
The present invention is further directed to a process for assembling a thrust plate assembly using the wear adjustment module described above, wherein the process comprises the following steps:
a) assembling the wear adjustment module;
b) arranging the wear adjustment module at an energy accumulator or a component of one of the housing and the pressure plate;
c) connecting of the constructional unit obtained in step b) with the others of the housing, the pressure plate, and the energy accumulator.
In step b), the wear adjustment module may be coupled with the energy accumulator in the area of a detection portion of the at least one detection element to obtain the constructional unit.
Further, it is possible that in step b) the second coupling area of the at least one adjusting pretensioning spring is arranged at the first component to obtain the constructional unit.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.